A collection of web sites with troubleshooting relevance:
a. Check out the Mac and Mac Clone Performance Comparison Page for dozens of pages of performance data.
b. Can't recall an obscure keyboard combination? Try the Mac Boot Key Combos page. Of course, the Shortcuts Apple Guide document (accessed from the Finder) is another useful source of this type of info.
c. The Daily Mac OS Info Page is yet another general Mac news page.